A physician typically accesses and visualizes tissue within a patient's gastrointestinal (GI) tract with a long, flexible endoscope. For the upper GI, a physician may insert a gastroscope into the sedated patient's mouth to examine and treat tissue in the esophagus, stomach, and proximal duodenum. For the lower GI, a physician may insert a colonoscope through the sedated patient's anus to examine the rectum and colon. Some endoscopes have a working channel, typically about 2.5-3.5 millimeters in diameter, extending from a port in the handpiece to the distal portion of the flexible insertion tube. A physician may insert medical devices into the working channel to help diagnose or treat tissues within the patient. Physicians commonly take tissue biopsies from the mucosal lining of the GI tract using a flexible, biopsy forceps through the working channel of the endoscope.
Insertion of a flexible endoscope, especially into the colon, can be a very time-consuming and uncomfortable procedure for the patient, even when the patient is sedated with drugs. A physician often needs several minutes to push a flexible endoscope through the convoluted sigmoid, and the descending, transverse, and ascending portions of the colon. The physician may diagnose and/or treat tissues within the colon either during insertion or removal of the endoscope. The flexible endoscope may “loop” within the colon, such as at the sigmoid colon or at the splenic flexure of the colon, so that it becomes difficult to further advance the endoscope along the colon. When a loop is formed, the force exerted to push the scope stretches the mesentery and causes pain for the patient. Depending on the anatomy of the patient and the skill of the physician in manipulating the flexible endoscope, some portions of the colon may be unexamined, thus increasing the risk of undiagnosed disease.
Guidewires have been used to aid the introduction of catheters and other instruments into many sites in the human body. Many medical applications and specific designs of guidewires have been for cardiovascular use. There are, however, specific challenges relating to the use of guidewires in the GI tract, as opposed to the vascular system. Thus, the bowel is more tortuous, softer and generally of larger diameter. Furthermore, in the case of the small intestine and the colon, these are longer than most arteries or veins.
Still, scientists and engineers continue to seek improved medical guidewires.